Apparatus and method for detecting battery cell failure due to unknown discharge current

ABSTRACT

A method for detecting failure of a battery cell due to an unknown discharge current, including connecting a detector in series between the battery cell and a power supply for supplying a charging power, determining whether the charging of the battery cell progresses by the charging power in excess of a predetermined battery cell specific charging reference time, measuring a current value of the battery cell in real time if the charging of the battery cell progresses in excess of the battery cell specific charging reference time, determining whether the current value of the battery cell measured in real time exceeds a predetermined battery cell specific failure determination reference current range value, and determining a state of the battery cell as a failure state if the current value of the battery cell exceeds the predetermined battery cell specific failure determination reference current range value.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of application Ser. No. 15/578,178filed on Nov. 29, 2017, which is the National Phase of PCT/KR2016/013550filed on Nov. 23, 2016, which claims the priority benefit of the KoreanPatent Application No. 10-2015-0168342 filed in the Republic of Korea onNov. 30, 2015, all of which are hereby incorporated by reference as iffully set forth herein.

TECHNICAL FIELD

The present invention relates to an apparatus and method for detectingfailure 15 of a battery cell due to an unknown discharge current, andmore particularly to an apparatus and method for detecting failure of abattery cell due to an unknown discharge current, which can reduce thetime required for failure detection compared to a conventional batterycell failure detection technique by using a real-time current monitoringmethod.

BACKGROUND ART

Recently, research and development on secondary batteries have beenactively conducted. Here, the secondary batteries, as batteries that canbe charged and discharged, mean that they include conventional Ni/Cdbatteries and Ni/MH batteries, and recent lithium ion batteries. Amongthe secondary batteries, the lithium ion battery has an advantage thatthe energy density is much higher than that of the conventional Ni/Cdbattery and Ni/MH battery, and further, the lithium ion battery can bemanufactured with a tendency of a small size so that it is used as apower source for a mobile apparatus. In addition, the usage range of thelithium ion battery extends as a power source for electric vehicles, sothat the lithium ion battery attracts attention as a next generationenergy storage medium.

Meanwhile, in the battery cell production process, an unknown dischargecurrent that may occur in a manufactured battery cell is a type offailure that abnormally drops the voltage of the battery cell. Theconventional technology for detecting the failure of a battery cellbased on the voltage characteristic of the battery cell takes a longperiod of time from the completion of the production of the battery cellto the time point when the failure is detected so that the productionrate of the battery cell is lowered.

Accordingly, the development of a new battery cell failure detectiontechnique using an unknown discharge current, which can reduce thedetection time compared to a conventional failure detection technique ofa battery cell based on the voltage characteristic of a battery cell inorder to increase the production speed of the battery cell, is required.

DISCLOSURE Technical Problem

The present invention provides a new apparatus and method for detectingfailure of a battery cell due to an unknown discharge current, which canreduce the detection time compared to a conventional battery cellfailure detection method using an unknown discharge current.

Technical Solution

In accordance with an exemplary embodiment, provided is a method fordetecting failure of a battery cell due to an unknown discharge current.The method includes: a detector connection operation of connecting adetector in series between the battery cell and a power supply forsupplying a charging power; a test proper charging time determinationoperation of determining whether the charging of the battery cellprogresses by the charging power in excess of a predetermined batterycell specific charging reference time; a current real-time measurementoperation of measuring a current value of the battery cell in real timeif the charging of the battery cell progresses in excess of the batterycell specific charging reference time; an unknown discharge currentmonitoring operation of determining whether the current value of thebattery cell measured in real time exceeds a predetermined battery cellspecific failure determination reference current range value; and afailure detection completion operation of determining a state of thebattery cell as a failure state in which an unknown discharge occurs ifthe current value of the battery cell exceeds the predetermined batterycell specific failure determination reference current range value.

The failure detection completion operation may further include a failuredetection notification operation of expressing the failure state throughat least one of a speaker, a display unit, and a lamp.

In accordance with another exemplary embodiment, provided is a methodfor detecting failure of a battery cell due to an unknown dischargecurrent, and the method includes: a detector connection operation ofconnecting a detector in series between the battery cell and a powersupply for supplying a charging power; a test proper charging timedetermination operation of determining whether the charging of thebattery cell progresses by the charging power in excess of apredetermined battery cell specific charging reference time; a currentreal-time measurement operation of measuring a current value of thebattery cell in real time if the charging of the battery cell progressesin excess of the battery cell specific charging reference time; abattery cell current accumulation storage operation of accumulating andstoring the real-time measured current value of the battery cell in astorage element for each measured time; a current slope variationcalculation operation of calculating a current slope variation of thecurrent value of the battery cell accumulated and stored in the batterycell accumulation storage operation; an unknown discharge currentmonitoring operation of determining whether the current slope variationcalculated in the current slope variation calculation operation exceedsa predetermined battery cell specific failure determination referencecurrent slope variation value; and a failure detection completionoperation of determining a state of the battery cell as a failure statein which an unknown discharge occurs if the current slope variationvalue exceeds the predetermined battery cell specific failuredetermination reference current slope variation value.

The failure detection completion operation may further include a failuredetection notification operation of expressing the failure state throughat least one of a speaker, a display unit, and a lamp.

In accordance with another exemplary embodiment, provided is anapparatus, which is connected in series between the battery cell and apower supply for supplying a charging power, for detecting failure of abattery cell due to an unknown discharge current, and the apparatusincludes: a storage element configured to store a battery cell specificfailure determination reference current range value and a battery cellspecific charging reference time in advance; a current measurement unitconfigured to measure a real-time current from the battery cell; and acontrol unit configured to determine whether the charging of the batterycell progresses by the charging power in excess of the battery cellspecific charging reference time, determine whether the current value ofthe battery cell measured in real time in the current measurement unitexceeds the battery cell specific failure determination referencecurrent range value if the charging of the battery cell progresses inexcess of the battery cell specific charging reference time, anddetermine a state of the battery cell as a failure state in which anunknown discharge occurs if the current value of the battery cellexceeds the battery cell specific failure determination referencecurrent range value.

The control unit may further include: a test proper charging timedetermination unit configured to determine whether the charging of thebattery cell progresses in excess of the battery cell specific chargingreference time; and a failure determination unit configured to determinewhether the current value of the battery cell measured in real timeexceeds the battery cell specific failure determination referencecurrent range value if the charging of the battery cell progresses inexcess of the battery cell specific charging reference time.

The apparatus may further include at least one of a speaker, a displayunit, and a lamp, wherein the control unit may further include a failuredetection notification unit configured to express the failure state ofthe battery cell through at least one of the speaker, the display unit,and the lamp.

In accordance with another exemplary embodiment, provided is anapparatus, which is connected in series between the battery cell and apower supply for supplying charging power, for detecting failure of abattery cell due to an unknown discharge current, and the apparatusincludes: a storage element configured to store a battery cell specificfailure determination reference current variation value and a batterycell specific charging reference time in advance; a current measurementunit configured to measure a real-time current from the battery cell;and a control unit configured to determine whether the charging of thebattery cell progresses in excess of the battery cell specific chargingreference time by the charging power, accumulate and store the currentvalue of the battery cell measured in real time in the currentmeasurement unit in the storage element for each measure time, calculatea current slope variation of the accumulated and stored current value ofthe battery cell, determine whether the calculated current slopevariation exceeds the battery cell specific failure determinationreference current variation value, and determine a state of the batterycell as a failure state in which an un unknown discharge failure occursif the current slope variation value exceeds a predetermined batterycell specific failure determination reference current slope variationvalue.

The control unit may further include: a test proper charging timedetermination unit configured to determine whether the charging of thebattery cell progresses in excess of the battery cell specific chargingreference time; and a battery cell current accumulation storage unitconfigured to accumulate and store a current value of the battery cellmeasured in real time in the current measurement unit in the storageelement for each measured time if the charging of the battery cellprogresses in excess of the battery cell specific charging referencetime; a current slope variation calculation unit configured to calculatethe current slope variation from the accumulated and stored currentvalue of the battery cell; and a current slope determination unitconfigured to determine whether the calculated current slope variationexceeds the battery cell specific failure determination referencecurrent variation value, and determine a state of the battery cell as afailure state in which an unknown discharge failure occurs if thecurrent slope variation value exceeds a predetermined battery cellspecific failure determination reference current slope variation value.

The apparatus may further include at least one of a speaker, a displayunit, and a lamp, wherein the control unit may further include a failuredetection notification unit configured to express the failure state ofthe battery cell through at least one of the speaker, the display unit,and the lamp.

Advantageous Effects

An apparatus and method for detecting a battery cell failure due to anunknown discharge current according to embodiments of the presentinvention include monitoring the current of a battery cell in real timeand diagnosing the failure of the battery cell due to an unknowndischarge current from the current of the monitored battery cell, indetecting the failure of the battery cell due to an unknown dischargecurrent, so it is possible to shorten the time required for aconventional technique to detect the failure of the battery cell due anunknown discharge current in order to shorten the production time of thefinal battery cell.

In addition, an apparatus and method for detecting a battery cellfailure due to an unknown discharge current according to embodiments ofthe present invention can detect a failure occurrence time of a batterycell due to an unknown discharge current, so that the failure detectioncan be performed immediately when the failure occurs.

DESCRIPTION OF DRAWINGS

FIG. 1 is an exemplary view illustrating voltage characteristics of anormal battery cell and a defective battery cell.

FIG. 2 is an exemplary illustrating an apparatus for detecting failureof a battery cell due to an unknown discharge current according to anembodiment of the present invention.

FIG. 3 is a detailed configuration view illustrating a detailedconfiguration of an apparatus for detecting failure of a battery celldue to an unknown discharge current according to an embodiment of thepresent invention.

FIG. 4 is a detailed configuration view illustrating a detailedconfiguration of an apparatus for detecting failure of a battery celldue to an unknown discharge current according to another embodiment ofthe present invention.

FIG. 5 is a flowchart illustrating a method for detecting failure of abattery cell due to an unknown discharge current according to anembodiment of the present invention.

FIG. 6 is a flowchart illustrating a method for detecting failure of abattery cell due to an unknown discharge current according to anotherembodiment of the present invention.

FIG. 7 is an exemplary view illustrating a measurement principle of anunknown discharge current according to embodiments of the presentinvention.

FIG. 8 is an exemplary view illustrating current characteristics of abattery cell in a failure state due to an unknown discharge current andbattery cells in a normal state.

FIG. 9 is an exemplary view illustrating a failure state detection timepoint of a defective battery cell due to an unknown discharge currentaccording to embodiments of the present invention.

MODE FOR INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. However, the presentinvention may be embodied in different forms and should not be construedas limited to the embodiments set forth herein, and rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art.

A battery cell according to an embodiment of the present invention maystore electrical energy and provide stored electrical energy. Here, thetype of a battery cell is not particularly limited. For example, thetype of the battery cell may include a lithium ion battery, a lithiumpolymer battery, a nickel cadmium battery, a nickel hydride battery, anickel zinc battery, and the like.

First, in order to help understanding an apparatus and method fordetecting a battery cell failure due to an unknown discharge currentaccording to embodiments of the present invention, a failure detectiontechnique of a battery cell due to a conventional unknown dischargecurrent will be described with reference to FIG. 1.

1. Conventional Failure Detection Technique of Battery Cell Based onVoltage Characteristics of Battery Cell

FIG. 1 is an exemplary view illustrating voltage characteristics of anormal battery cell and a defective battery cell.

Referring to FIG. 1, a voltage characteristic of a battery cell in adefective state is sharply decreased over time as compared with avoltage characteristic of a battery cell in a normal state. Aconventional battery cell failure detection technique based on suchvoltage characteristics performs the failure detection of a battery cellthrough following processes.

Operation of charging a produced battery cell for a predetermined time.

Operation of measuring the voltage of the charged battery cell once.

Operation of re-measuring the voltage of the battery cell several daysafter the one time measurement.

Operation of determining whether a voltage difference between theinitially measured voltage and the re-measured voltage has a value equalto or greater than a predetermined defective battery cell determinationreference value.

A failure detection operation of determining that an unknown dischargecurrent failure occurs in the battery cell when the voltage differencehas a value equal to or larger than a predetermined defective batterycell determination reference value.

The conventional battery cell failure detection technology based on thevoltage characteristics of a conventional battery cell, which isperformed in the above operations, has a problem in that it takesseveral days to detect the failure due to the unknown discharge currentof the produced battery cell.

In addition, since the conventional defective detection technology of abattery cell based on the voltage characteristic of a conventionalbattery cell is applied and the time required for the defectiveinspection up to the production of a good battery cell is included, thiscauses the production unit price to rise.

On the other hand, since an apparatus and method for detecting a batterycell failure due to an unknown discharge current according toembodiments of the present invention are based on the currentcharacteristics of a battery cell due to an unknown discharge current,it is possible to reduce the time required for detecting the failure ofa battery cell.

2. Apparatus for Detecting Failure of Battery Cell Due to UnknownDischarge Current According to Embodiment of Present Invention

FIG. 2 is an example view illustrating an apparatus for detectingfailure of a battery cell due to an unknown discharge current accordingto an embodiment of the present invention, and FIG. 3 is a detailedconfiguration view illustrating a detailed configuration of an apparatusfor detecting failure of a battery cell due to an unknown dischargecurrent according to an embodiment of the present invention.

Referring to FIG. 2, the apparatus 100 for detecting failure of abattery cell due to an unknown discharge current according to anembodiment of the present invention includes a battery cell 200 isconnected in series between a battery cell 200 and a power supply 300for supplying a charging power to the battery cell 200, so that it ispossible to detect whether the battery cell 200 is in a defective statedue to an unknown discharge current.

The battery cell 200 may be charged by the charging power supplied fromthe power supply 300.

The apparatus 100 for detecting failure of a battery cell due to anunknown discharge current may detect a failure due to an unknowndischarge current with respect to the battery cell 200.

Referring to FIG. 3, the apparatus 100 for detecting failure of abattery cell due to an unknown discharge current according to anembodiment of the present invention may be configured including acurrent measurement unit 110, a storage element 120, and a control unit160.

The apparatus 100 for detecting failure of a battery cell due to anunknown discharge current according to an embodiment of the presentinvention may be configured further including at least one of a speaker130, a display unit 140, and a lamp 150 according to specifications.

The current measurement unit 110 may measure the current of the batterycell 200 in real time according to the control of the control unit 160.

The storage element 120 may store a battery cell specific failuredetermination reference current range value and a battery cell specificcharging reference time according to the control of the control unit 160in advance. Herein, the battery cell specific charging reference timemay include battery cell specific minimum charging time information inorder for charging to proceed before the battery cell 200 startsdetecting a failure due to the unknown discharge current.

The battery cell specific failure determination reference current rangevalue may include battery cell specific current values of a normal statewith respect to a charging time. The battery cell specific failuredetermination reference current range value may be used as a referencevalue that is used to determine a failure due to an unknown dischargecurrent.

The control unit 160 may include a test proper charging timedetermination unit 161, a failure determination unit 162, and a failuredetection notification unit 163.

The test proper charging time determination unit 161 may determinewhether the charging of the battery cell 200 exceeds the battery cellspecific charging reference time stored in advance in the storageelement 120 by the charging power of the power supply 300. In order toaccurately detect a failure due to an unknown discharge current of thebattery cell 200 without error, the charging must be performed in excessof a predetermined charging time for each battery cell.

If the charging of the battery cell 200 proceeds beyond the battery cellspecific charging reference time stored in advance in the storageelement 120, the failure determination unit 162 may determine whetherthe current value of the battery cell 200 measured in real time in thecurrent measurement unit 110 exceeds the battery cell specific failuredetermination reference current range value stored in advance in thestorage element 120.

If the current value of the battery cell 200 measured in real timeexceeds the battery cell specific failure determination referencecurrent range value stored in advance in the storage element 120, thefailure determination unit 162 may determine the state of the batterycell 200 as a failure state in which an unknown discharge occurs.

When the failure determination unit 162 determines the state of thebattery cell 200 as a failure state, the failure detection notificationunit 163 may express the state of the battery cell 200 as a failurestate through at least one of the speaker 130, the display unit 140, andthe lamp 150.

3. Method for Detecting Failure of Battery Cell Due to Unknown DischargeCurrent According to Embodiment of Present Invention

FIG. 5 is a flowchart illustrating a method for detecting failure of abattery cell due to an unknown discharge current according to anembodiment of the present invention.

Referring to FIG. 5, the apparatus 100 for detecting failure of abattery cell due to an unknown discharge current according to anembodiment of the present invention may perform a detector connectionoperation (S510) to be connected in series between the battery cell 200and the power supply 300 for supplying a charging power to the batterycell 200.

Thereafter, the control unit 160 of the apparatus 100 for detectingfailure of a battery cell due to an unknown discharge current mayperform a test proper charging time determination operation (S520) ofdetermining whether the charging of the battery cell 200 proceeds beyondthe battery cell specific charging reference time stored in advance inthe storage element 120 by the charging power supplied from the powersupply 300.

If the charging of the battery cell 200 proceeds beyond the battery cellspecific charging reference time stored in advance in the storageelement 120, the control unit 160 may perform a current real-timemeasurement operation (S530) of measuring the current value of thebattery cell 200 in real time through the current measurement unit 110.

Thereafter, the control unit 160 may perform an unknown dischargecurrent monitoring operation (S540) of determining whether the currentvalue of the battery cell 200 measured in real time in the currentmeasurement unit 110 exceeds a battery cell specific failuredetermination reference current range value stored in advance in thestorage element 120.

If the current value of the battery cell 200 measured in real timeexceeds the battery cell specific failure determination referencecurrent range value stored in advance in the storage element 120, thecontrol unit 160 may perform a failure detection completion operation(S550) of determining the state of the battery cell 200 as a failurestate in which an unknown discharge occurs.

In addition, the failure detection completion operation (S550) performedby the control unit 160 may include a failure detection notificationoperation of expressing a failure state of the battery cell 200 throughat least one of the speaker 130, the display unit 140, and the lamp 150.

4. Apparatus for Detecting Failure of Battery Cell Due to UnknownDischarge Current According to Another Embodiment of Present Invention

FIG. 4 is a detailed configuration view illustrating a detailedconfiguration of an apparatus for detecting failure of a battery celldue to an unknown discharge current according to another embodiment ofthe present invention.

Referring to FIG. 4, an apparatus 100 for detecting failure of a batterycell due to an unknown discharge current according to another embodimentof the present invention may be configured including a currentmeasurement unit 110, a storage element 120, and a control unit 160.

The apparatus 100 for detecting failure of a battery cell due to anunknown discharge current according to another embodiment of the presentinvention may be configured further including at least one of a speaker130, a display unit 140, and a lamp 150 according to specifications.

Except for the stored information of the storage element 120 and someconfiguration of the control unit 160, the apparatus 100 for detectingfailure of a battery cell due to an unknown discharge current accordingto another embodiment of the present invention is identical to theapparatus 100 for detecting failure of a battery cell due to an unknowndischarge current according to an embodiment of the present invention,which is described in detail with reference to FIG. 1. Therefore,detailed description of the same components as those of FIG. 1 will beomitted.

The storage element 120 may store a battery cell specific failuredetermination reference current range variation value and a battery cellspecific charging reference time according to the control of the controlunit 160 in advance. Herein, the battery cell specific chargingreference time may include battery cell specific minimum charging timeinformation in order for charging to proceed before the battery cell 200starts detecting a failure due to the unknown discharge current. Thebattery cell specific failure determination reference current rangevariation value may include battery cell specific current variationvalues of a normal state with respect to a charging time. The batterycell specific failure determination reference current range variationvalue may be used as a reference value that is used to determine afailure due to an unknown discharge current.

The control unit 160 may be configured including a test proper chargingtime determination unit 161, a battery cell current accumulation storageunit 164, a current slope variation calculation unit 165, a currentslope determination unit 166, and a failure detection notification unit163.

The test proper charging time determination unit 161 may determinewhether the charging of the battery cell 200 exceeds the battery cellspecific charging reference time stored in advance in the storageelement 120 by the charging power of the power supply 300. In order toaccurately detect a failure due to an unknown discharge current of thebattery cell 200 without error, the charging must be performed in excessof a predetermined charging time for each battery cell.

If the charging of the battery cell 200 proceeds beyond the battery cellspecific charging reference time stored in advance in the storageelement 120, the battery cell current accumulation storage unit 164 mayaccumulate and store the current value of the battery cell 200, which ismeasured in real time, in the current measurement unit 110 for eachmeasured time.

Thereafter, the current slope variation calculation unit 165 maycalculate the current slope variation from the current value of thebattery cell 200 accumulated in the storage element 120 by the batterycell current accumulation storage unit 164.

Thereafter, the current slope determination unit 166 may determinewhether the current slope variation calculated by the current slopevariation calculation unit 165 exceeds a battery cell failuredetermination reference current variation value stored in advance in thestorage element 120.

Thereafter, if the current slope variation calculated by the currentslope variation calculation unit 165 exceeds the battery cell failuredetermination reference current variation value stored in advance in thestorage element 120, the current slope determination unit 166 maydetermine the state of the battery cell 200 as a failure state in whichan unknown discharge failure occurs.

When the current slope determination unit 166 determines the state ofthe battery cell 200 as a failure state, the failure detectionnotification unit 163 may express the state of the battery cell 200 as afailure state through at least one of the speaker 130, the display unit140, and the lamp 150.

5. Method for Detecting Failure of Battery Cell Due to Unknown DischargeCurrent According to Another Embodiment of Present Invention

FIG. 6 is a flowchart illustrating a method for detecting failure of abattery cell due to an unknown discharge current according to anotherembodiment of the present invention.

Referring to FIG. 6, the apparatus 100 for detecting failure of abattery cell due to an unknown discharge current according to anotherembodiment of the present invention may perform a detector connectionoperation (S610) to be connected in series between the battery cell 200and the power supply 300 for supplying a charging power.

Thereafter, the control unit 160 of the apparatus 100 for detectingfailure of a battery cell due to an unknown discharge current mayperform a test proper charging time determination operation (S620) ofdetermining whether the charging of the battery cell 200 proceeds beyondthe battery cell specific charging reference time stored in advance inthe storage element 120 by the charging power supplied from the powersupply 300.

If the charging of the battery cell 200 proceeds beyond the battery cellspecific charging reference time stored in advance in the storageelement 120, the control unit 160 may perform a current real-timemeasurement operation (S630) of measuring the current value of thebattery cell 200 in real time through the current measurement unit 110.

Thereafter, the control unit 160 may perform a battery cell currentaccumulation storage operation (S640) of accumulating and storing thecurrent value of the battery cell 100, which is measured in real time,in the storage element 120 for each measured time.

Thereafter, the control unit 160 may perform a current slope variationcalculation operation (S650) of calculating a current slope variationfrom the current value of the battery cell 200 accumulated and stored inthe storage element 120 in the battery cell current accumulation storageoperation (S640).

Thereafter, the control unit 160 may perform an unknown dischargecurrent monitoring operation (S660) of determining whether the currentslope variation value calculated in the current slope variationcalculation operation (S650) exceeds the battery cell specific failuredetermination reference current slope variation value stored in advancein the storage element 120.

If the calculated current slope variation value exceeds the battery cellspecific failure determination reference current slope variation valuestored in advance in the storage element 120, the control unit 160 mayperform a failure detection completion operation (S670) of determiningthe state of the battery cell 200 as a failure state in which an unknowndischarge occurs.

In addition, the failure detection completion operation (S670) performedby the control unit 160 may include a failure detection notificationoperation of expressing a failure state of the battery cell 200 throughat least one of the speaker 130, the display unit 140, and the lamp 150.

6. Measurement Principle of Unknown Discharge Current According toEmbodiments of Present Invention

FIG. 7 is an exemplary view illustrating a measurement principle of anunknown discharge current according to embodiments of the presentinvention.

Referring to FIG. 7, the battery cell 200 may be represented by anequivalent circuit as shown on the right side.

A current A represents the current of the battery cell 200 in adefective state having a resistance component causing an unknowndischarge current.

A current B represents the current of the battery cell 200 having aresistance component that induces a basic self-discharge current.

A current C represents the current charged in the battery cell 200 whenvoltage is applied by the charging power supplied by the power supply300.

In the normal state of the battery cell 200, only the current B and thecurrent C are applied to the inside of the battery cell 200 by the powersupply 300, and the current A does not exist.

Thereafter, as the battery cell 200 in the normal state is charged andbecomes a fully charged state, the current C decreases and only thecurrent B exists, so that the total amount of current decreases.

More specifically, FIG. 8 is an exemplary view illustrating currentcharacteristics of a battery cell in a failure state due to an unknowndischarge current and battery cells in a normal state.

Referring to FIG. 8, in relation to the current characteristic of theA-class cell in the normal state, as the charging progresses and becomesa fully charged state, the total amount of current decreases. Inrelation to the rest of the cells except the A-class cells, as thecharging progresses and becomes a fully charged state, the total amountof current rapidly increases or slowly increases in proportion to theincrease amount of the current A.

FIG. 9 is an exemplary view illustrating a failure state detection timepoint of a defective battery cell due to an unknown discharge currentaccording to embodiments of the present invention.

Referring to FIG. 9, the apparatus 100 for detecting failure of abattery cell due to an unknown discharge current according toembodiments of the present invention may immediately detect itimmediately when the total amount of current increases due to an unknowndischarge current in the battery cell 200 being charged by using thecurrent characteristics of the battery cell 200 described with referenceto FIGS. 8 and 9. Therefore, it is possible to reduce the time requiredfor failure detection as compared with the conventional battery cellfailure detection technique based on voltage characteristics.

On the other hand, although the technical idea of the present inventionis specifically described with reference to the above embodiments, itshould be noted that the above embodiments are for the purpose ofexplanation and not for the purpose of limitation. It will be apparentto those skilled in the art that various modifications and variationscan be made in the present invention without departing from the spiritand scope of the invention.

What is claimed is:
 1. A method for detecting failure of a battery cell due to an unknown discharge current, the method comprising: supplying power to the battery cell operation of connecting a power supply to the battery cell for supplying power to the battery cell and connecting a detector in series between the battery cell and a power supply; a current real-time measurement operation of measuring a current value of the battery cell in real time; a battery cell current accumulation storage operation of accumulating and storing the real-time measured current value of the battery cell in a storage element for each measured time; a current slope variation calculation operation of calculating a current slope variation of the current value of the battery cell accumulated and stored in the battery cell accumulation storage operation; an unknown discharge current monitoring operation of determining whether the current slope variation calculated in the current slope variation calculation operation exceeds a predetermined battery cell specific failure determination reference current slope variation value; and a failure detection completion operation of determining a state of the battery cell as a failure state in which an unknown discharge occurs when the current slope variation value exceeds the predetermined battery cell specific failure determination reference current slope variation value, and further including: determining as the supplying a power to the battery cell progresses, whether the current decreases or increases; when the current decreases as the supplying a power to the battery cell progresses, designating the battery cell as normal and continue a production process of the battery cell; and when the current decreases as the supplying a power to the battery cell progresses, designating the battery cell as being in the failure state and removing the battery cell from the production process.
 2. The method of claim 1, wherein the failure detection completion operation further comprises a failure detection notification operation of expressing the failure state through at least one of a speaker, a display unit, and a lamp. 